Make HAProxy forward requests to a hostname instead of IP address.

Question

I have 3 virtual hosts on a single IP address.Host_a, Host_b and Host_c all mapping to 192.168.1.10.

My HAProxy configuration is as follows:

frontend http   
.
.
.
acl host_one   path_end -i /ABC/application
acl host_two   path_end -i /XYZ/application
acl host_three path_end -i /PQR/application

use_backend be_host1    if host_one
use_backend be_host2    if host_two
use_backend be_host3    if host_three

backend be_host1
    server channel Host_a

backend be_host2 
    server channel Host_b

backend be_host3 
    server channel Host_c

Now for example, HAproxy forwards request to 192.168.1.10/ABC/application in case it matches an incoming URL ending with /ABC/application. Is there a way I could forward it to http://Host_a/ABC/application instead ? It is important for me that they use the hostname instead of its corresponding IP address.

Answer 1

The hostname is a part of the HTTP request, and that means you can use the HAProxy option reqirep to set it to whatever you want.

reqirep ^Host:   Host:\ Host_a

You can use this type of option in all three of your backends.